/Engine/Source/Runtime/Engine/Public/MaterialCompiler.h
Register an operator of the tree representation the Strata material and its topology.
[FStrataOperator](API\Runtime\Engine\Rendering\FStrataOperator) & StrataCompilationRegisterOperator ( int32 OperatorType, [FGuid](API\Runtime\Core\Misc\FGuid) StrataExpressionGuid, [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * Child, [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * Parent, [FGuid](API\Runtime\Core\Misc\FGuid) StrataParentExpressionGuid, bool bUseParameterBlending )